Fire crews fight blaze in student apartment block

Two people have been taken to hospital and almost 400 people have been evacuated from a Sydney apartment block after an early morning fire.

Rick Parkes from New South Wales Fire and Rescue says the blaze at the Uni Lodge in Ultimo started around 4:30am.

He says the Broadway shopping centre opposite the scene of the fire was opened to let the evacuees stay out of the rain.

"Across the road in Bay Street, there's the Broadway shopping mall ... and people have been allowed in there where it's a little bit warmer in the foyer area to keep themselves warm until they're allowed back into their rooms," he said.

It is believed a spark in a switchbox on the building's second floor started the fire.